60 Brady and Crosskey — Notes on Fossil Ostracoda. 



Appendix. — As bearing on tlie foregoing, I add the following 

 translation of M. Chancourtois's remarks on the probable origin of 

 diamonds, from "■ Silliman's American Journal of Science and Arts," 

 2nd ser,, vol. xlii., p. 271 : — 



" E. B. de Chancourtois has presented the view that the diamond has been formed 

 from hydrocarburetted emanations, as sulphur is formed from hydrosulphuretted 

 emanations, and that its origin is thus connected with the previous existence of petro- 

 leum-bearing or bituminous schists. In the oxydation of sulphuretted hydrogen in 

 solfataras, all the hydrogen is oxydized, but only a part of the sulphur passes to the 

 state of sulphurous acid in this humid process of combustion. So, in an analogous 

 manner, the diamond was probably formed ; that is, in the course of the humid com- 

 bustion of a carburetted hydrogen, in which all the hydrogen was oxydized, but only 

 a part of the carbon was transformed into carbonic acid. This view accords with the 

 occurrence of the diamond in arenaceous rocks, or itacolumites, which are mostly 

 metamorphic rocks of palaeozoic age, and which may have once been bituminous, 

 either by original formation or by emanations from lower rocks. 



" M. Chancourtois supposes that the crystal would have formed only where there 

 were fissures for the passage of the vapours of the carburetted hydrogen, and where 

 the process could go on with extreme slowness." Les Mondes, July 19, 1866, p. 438. 



The Editor of the American Journal adds : — " The author does not appear to con- 

 nect the process of formation with that of the metamorphism to which the diamond- 

 bearing rocks have undoubtedly been subjected, and which may have been essential to 

 the result." 



The Carboniferous strata of the United States, which in Pennsylvania yield 

 anthracite instead of coal, have in Massachussetts been so much further metamor- 

 phosed that they consist of gneiss, quartzite, bands of plumbaginous anthracite, 

 pyritiferous clay-slate, mica-schist with garnets and veins of asbestos, and graphitic 

 schists (Hitchcock and Lyell). At places where further metamorphism may have 

 affected such granitiferous and graphitic schists, diamonds may of course be looked 

 for, in association with garnets, etc., in the local drift. 



II. — Notes on Fossil Osteacoda from the Post-Tertiaky 

 Deposits of Canada and New England. 



By George Stewardson Brady, C.M.Z.S., and H. W. Crosskey, F.G.S. 

 PLATE II. 



WE are indebted for the material from which the following notes 

 have been compiled to Principal Dawson, of Montreal, and to 

 the Secretary of the Portland Society of Natural History, to whom 

 our best thanks are due for the opportunity thus afforded us of 

 comparing the fossils of the North American Clay Beds with those 

 of our own country. By carefully washing the clays kindly for- 

 warded to us, we have obtained many specimens in excellent con- 

 dition for examination. 



Of the thirty-three species here noticed, twenty-three are well 

 known to us as occurring in the Scottish Glacial Clays, twenty-five 

 are living inhabitants of the British Seas, while six (Gy there cuspidata, 

 G. MacGhesneyi, G. Logani, Gytherura granulosa, G. cristata, Gytliero- 

 pteron complanatum) are new to science, being here for the first time 

 described. 



We know too little of the recent American Ostracoda to institute 

 any very precise comparison between them and the fossil fauna 

 represented by the following list of species ; but when compared with 

 British collections, we find the contents of the Canadian fossiliferous 



